Machinability of SiCf/SiC ceramic matrix composites using longitudinal-torsional coupled rotary ultrasonic machining.

SiCf/SiC ceramic matrix composites are widely used in high-tech fields such as aerospace and usually processed by grinding methods. In the conventional machining (CON-M), the cutting force during machining is increased due to the hard and brittle characteristics of the material, which affects the surface topography after machining. As a new machining method, longitudinal-torsional coupled rotary ultrasonic machining (LTC-RUM) can effectively reduce the cutting force and improve the surface topography after machining. The machining characteristics of SiCf/SiC ceramic matrix composites in LTC-RUM was investigated to improve the service performance of the material, and reduce the energy consumption. However, relatively few studies have been performed on the machinability of SiCf/SiC ceramic matrix composites by LTC-RUM. This paper studies the cutting force and surface topography during machining by experimental methods. Firstly, the motion characteristics of a single abrasive grain during LTC-RUM are analyzed, and the cutting characteristics of the abrasive grain under the both machining conditions are obtained. Secondly, the effects of spindle speed, feed rate, cutting depth, and ultrasonic amplitude on cutting force and surface roughness were obtained by experimental exploration of CON-M and LTC-RUM. Compared with CON-M, the cutting force is reduced by 64.4%, the surface roughness is reduced by 44.5% under LTC-RUM, and the surface topography is significantly improved. The results of this study provide a theoretical and experimental basis for machining SiCf/SiC ceramic matrix composites. [ABSTRACT FROM AUTHOR]